1. Field of the Invention
The present invention is related to an actuator, in particular, to an actuator with multi-stage gears.
2. Description of Related Art
Actuators used in such as conference tables, electric hospital beds, fitness equipment and wheel chairs for adjusting and modifying the height and tilting angle of the positions thereof are common and applied widely.
Traditional actuators typically comprise a worm gear shaft driving assembly, an electric motor and a planetary gear assembly. The worm gear shaft driving assembly comprises a worm gear; the electric motor comprises a transmission shaft; the planetary worm gear assembly comprises an annulus gear, a sun gear and a plurality of planetary gears. The annulus gear is connected to the worm gear shaft and comprises an inner gear at an inner circumferential edge thereof; the sun gear is connected to the transmission shaft and is provided at the inner portion of the inner gear; the plurality of the planetary gears are engaged with the inner gear and the sun gear such that the worm gear shaft driving assembly is connected to the electric motor via the planetary gear assembly in order to allow the transmission shaft to stably drive the worm gear shaft to rotate.
However, as modern products are designed to be lighter in weight and smaller in size, the actuator installed inside the product would also be required to be of the characteristic of being light in weight and small in size. Nevertheless, since the aforementioned annulus gear, sun gear and the planetary gear must engage with each other and the gear teeth path needs to be within a predetermined value, the volume of the planetary gear assembly cannot be reduced, which in turns poses difficulties in reducing the volume of the actuator.
In view of the above, the inventor of the present invention seeks to overcome the aforementioned drawbacks of the currently existing technology with great efforts in research and development along with the use of theories, which serves as the goal for improvement the inventor wishes to accomplish.